Math Trigonometry The opposite and adjacent

Opposite side and adjacent leg

Prerequisite for sine, cosine, and tangent of an angle is a right triangle.

We have already clarified the difference between the cathetus and the hypotenuse in the Pythagorean theorem. However, if you now look at one of the other two angles (not the right one), they always have an opposite and adjacent.



  • The opposite is the side of the triangle opposite the chosen angle.
  • The adjacent, the other cathetus is called, which abuts the angle.